Fill every row, column and box with 1 to 9
Every puzzle is generated fresh and has exactly one solution — no guessing is ever required. Pick a level to begin.
Each of the nine rows, the nine columns and the nine 3×3 boxes must contain the digits 1 to 9 exactly once. The digits printed at the start never change; everything else is for you to work out.
Tap a square and choose a digit, or use the keyboard: 1–9 to write, Backspace to clear, arrow keys to move. Switch on pencil marks to jot down candidates in a square, and use Undo to step back through your moves.
Mistakes are flagged as soon as a wrong digit is written. Turn checking off in Notes-only play if you prefer to find them yourself.
Sudoku reached the world by a roundabout route. A puzzle of the same shape appeared in French newspapers in the 1890s, then the modern version was published in 1979 by an American architect, Howard Garns, under the name Number Place. It found its real audience in Japan, where the publisher Nikoli renamed it in 1984 and added the rules that give it its character — a limited number of starting digits, placed in a symmetrical pattern.
It became a global habit two decades later, when a New Zealand judge named Wayne Gould, who had written a program to generate puzzles, persuaded The Times of London to print one in 2004. Within months newspapers everywhere carried a daily grid. The appeal is that it needs no arithmetic and no language at all: the digits are simply nine distinct symbols, so the same puzzle works unchanged in any country.
A properly made puzzle has exactly one solution and can be reached by reasoning alone, never by guesswork — that constraint is what separates a good grid from a bad one, and it is why difficulty depends on which techniques are required rather than on how many digits are missing. Solvers keep coming back because progress is entirely their own: every digit placed is a small proof, and a finished grid is the record of it.